1. Field of the Invention
This invention relates to an apparatus and method for detecting substances including glucose in a fluid to be collected from tissue.
2. Discussion of the Art
Glucose is an important substance for biological activities. For example, in individuals who may be affected by diabetes, there is a need to detect or measure the presence and amount of glucose as part of a daily routine. However, currently available measurement techniques often involve invasive testing. One method of glucose testing includes blood based assay testing. The xe2x80x9cfinger stickxe2x80x9d blood assay testing technique currently is one widely accepted methodology for glucose testing results in the United States. Of course, this invasive approach requires that the drawing of blood to perform the test. This is quite uncomfortable to patients, especially to young patients. Moreover, this approach is time consuming.
Therefore, it is desirable to provide non-invasive or minimally-invasive techniques for measuring substances, such as glucose concentration, from fluids, such as blood and interstitial fluid.
Briefly, the present invention is directed to a system and method for detecting substances, such as glucose, in a fluid to be collected from a tissue. In one aspect, the system according to the present invention has an assay device and an optical apparatus. The assay device is suitable for attachment to the tissue, wherein the assay device is a dual function device that includes a reactive region that is responsive to at least one substance in fluid to be collected from the tissue when the fluid is in contact with the reactive region, and which reactive region is also responsive to a first type of optical energy suitable to heat up and transfer heat by conduction to the tissue to ablate the tissue and form at least one opening in the tissue from which fluid is collected. The optical apparatus has an activation head to which the assay device is attached, and a first optical energy source that outputs the first type of optical energy. An optical detecting device is included in the optical apparatus to measure a characteristic of the at least one substance from the response of the reactive region when the reactive region is in contact with the at least one substance in fluid.
In another aspect, the present invention provides a method for detecting a substance, such as glucose, in a fluid from a tissue. The method includes the steps of placing an assay on an activation head of an optical instrument, wherein the assay is responsive to at least one substance, positioning the activation head to the surface of the tissue so that the assay is in contact with the surface of the issue, forming at least one opening underneath the assay through the surface of the tissue, thereby to allow the fluid from the tissue to flow through the at least one opening and make contact with the assay, and detecting the response of the assay to the fluid to measure the presence of the at least one substance in the fluid. The method can be practiced by using the system in accordance with a preferred embodiment of the present invention.
According to yet another aspect of the present invention, an assay device is provided that includes a base having a first side and a second side, and a reactive region disposed or deposited on the first side of the base. The reactive region comprises a photosensitizing material that is placed in contact with the surface of the tissue and is responsive to a suitable electromagnetic energy emitted thereon so as to heat up and conductively transfer heat to the surface of the tissue to form at least one opening, thereby to allow fluid from the tissue through the at least one opening to contact with the assay. Moreover, the photosensitizing material is further responsive to at least one substance in the fluid, from which a characteristic of the at least one substance is detected based upon electromagnetic energy scattered and/or reflected therefrom.